I leave my fenders on all year. It was funny, because during STP it was blazing sun and in the upper 90s, and I'm cranking along with my fenders on. A guy from one of the eastern WA clubs was joking with me and said "it's sure a good thing you've got those fenders on there today", and I told him it was to protect my tires from sun damage. I'm not sure if he thought I was serious or not.
